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Marine Habitat Classification


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1 result for 'CR.HCR.XFa.ByErSp.Cyl'

   CR.HCR.XFa.ByErSp.Cyl  Mixed turf of bryozoans and erect sponges with Cylista elegans on tide-swept ciraclittoral rock

This variant is typically found on wave-exposed circalittoral bedrock and boulders, on steep slopes and upper faces in moderate tidal streams. This species-rich biotope is characterised by a dense sponge, hydroid and bryozoan turf and frequent Alcyonium digitatum. There are frequently large growths of Cliona celata and Pachymatisma johnstonia. Other species present in this diverse sponge community include Polymastia boletiformis, Haliclona viscosa, Polymastia mamilliaris, Sycon ciliatum, Hemimycale columella and Dysidea fragilis. Axinellid sponges such as Stelligera stuposa and Raspailia ramosa may be present in low abundance, and are usually more abundant in deeper water. A dense hydroid turf forms a significant part of this biotope, with tufts of large hydroids such as Nemertesia antennina and Nemertesia ramosa frequently recorded. Other hydroid turf component species include Halecium halecinum, Aglaophenia tubulifera and Abietinaria abietina. Anemones are also well represented, with species such as Urticina felina, Cylista elegans and Metridium senile recorded. The cup coral Caryophyllia smithii and the anemone Corynactis viridis are also frequently seen. The bryozoan turf is composed predominantly of Alcyonidium diaphanum and Flustra foliacea, whilst crustose species such as Parasmittina trispinosa contribute to a lesser extent. The delicate Crisularia plumosa may also be present. There is a significant echinoderm component in this biotope. Species such as the starfish Asterias rubens, Henricia oculata, Marthasterias glacialis and Luidia ciliaris, the sea urchin Echinus esculentus and the crinoid Antedon bifida are all regularly recorded. Other species which may be observed include the top shell Calliostoma zizyphinium, the colonial ascidian Clavelina lepadiformis and the barnacle Balanus crenatus. The crab Cancer pagurus is typically found under boulders. This variant has been recorded from from various sites including Pembrokeshire, the Calf of Man and the west coast of Ireland.
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